Countertop Partial Mashing

What do you get when you combine partial mashing, batch sparging and the extract late method of extract brewing? An easy, flexible way to brew better beer on your stovetop -- countertop partial mashing.

We'll take you step by step through this procedure and point out its many benefits along the way. Plus: Three partial mash recipes and two web-only bonus recipes!

Most homebrewers identify themselves either as extract or all-grain brewers, but there’s another division that may be just as important — stovetop brewers or outside brewers.

Generally, extract brewers brew in their kitchen, on their stovetop, whereas most all-grain brewers are outside brewers — or at least outside-of-the-kitchen brewers. However, there are many exceptions. Some all-grain brewers do brew in their kitchen, using their kitchen stove to heat their kettle. Likewise, some extract brewers boil their wort with a turkey fryer out on their driveway or patio.

Back when I was an apartment dweller, living in Boston, I was a stovetop brewer — starting with extract beers and moving on to all-grain later. In the cramped space of my apartment kitchen, I found problems with both methods. When I made extract beer — boiling a “thick” wort, then diluting it in my fermenter — my beer always turned out too dark and not hoppy enough. When I made all-grain beers, the equipment took up a ton of space and I had difficulty bringing the 6 gallons (23 L) of wort I would collect to a rolling boil on my stove.

These days, I live in a house in Texas and brew out on my carport, but sometimes, there are problems with that, too. For example, last year, when I brewed the official batch of BYO’s 10th Anniversary Ale, it was 110 °F (43 °C) outside. Under my carport, with all the burners going, it was 113 °F (45 °C). Inside, my kitchen was air-conditioned. That day, I started thinking about a way to brew in my kitchen again. I wanted a method that avoided the problems associated with boiling a thick, extract wort, but had (at least most of) the flexibility of all-grain brewing.

Then one day, walking through The Sports Authority — an Austin sporting goods store — it dawned on me.

All the bits and pieces of my solution have been presented in Brew Your Own before. Back in the October 2002 issue, Mark Henry wrote an article titled “Beer The Partial Mash Way,” outlining one method of partial mashing. In the same issue, Steve Bader wrote an article on the then-new “extract late” method of extract brewing. And finally, in the January 2004 issue, Denny Conn wrote about batch sparging, a lautering method for all-grain brewers.

All these disparate threads came together when I saw a 2-gallon (7.6 L) insulated beverage cooler in the camping section of Sports Authority. (And no, the thought of exercising never occurred to me while in the store, I was only there looking for camping gear that I could convert into equipment for my home brewery.)

The basics of my idea are this: You mash 4.0 lbs. (1.8 kg) of grain in a 2.0-gallon (7.6-L) beverage cooler. To avoid having to make any conversions to the cooler, you use a batch sparge procedure for collecting your wort. The roughly 3.0 gallons (11 L) of wort you make in the mini-mash is boiled, along with your hops, down to 2.5 gallons (9.5 L) on your stovetop. At or near the end of the boil, you add light liquid malt extract to achieve the total amount of fermentables you require. Finally, after cooling your wort, you dilute it with water to 5.0 gallons (19 L).

This method combines the benefits of the “extract late” method of extract brewing, with the flexibility of partial mashing — and it can all be done in your kitchen, while only taking up an extra foot or two of counter space.
There are many other benefits to this procedure and I’ll explain them — as well as the one potential pitfall — as I walk you through a brewday of countertop partial mashing.

Four Pounds of Grain

At the heart of this method is 4.0 lbs. (1.8 kg) of grain — whatever specialty grains the recipe calls for with the remainder being base malt. And, you can use any base malt you want. For example, you can use 2-row pale or pale ale malt, including malts made from Maris Otter or Golden Promise barley. You can use Munich or Vienna malt. You can use wheat or rye malts. Many of these base grains are either unavailable or hard to find in malt extract form.
You can even use a limited amount of starchy adjuncts — such as flaked maize, flaked oats or flaked barley — up to around 13 oz. (0.36 kg) per 5.0-gallon (19-L) batch when mashed with most 2-row pale malts. (You can use up to 19 oz. (0.54 kg) of starchy adjunct if you use a 6-row base malt.) Starchy adjuncts can’t be steeped, but using a partial mash procedure allows stovetop brewers to utilize these grains in their brewing. Basically — with my countertop, batch sparging, partial mash procedure — you can use any base malt available to all-grain brewers, and limited amounts of any starchy adjunct.

As with a full, all-grain mash, you can mash at a “low” mash temperature — 148–152 °F (64–67 °C) — and make a highly fermentable wort. Likewise, you can mash at a “high” mash temperature — 156–162 °F (69–72 °C) and make a less fermentable wort. Your overall wort fermentability will depend both on your mash temperature (and hence the fermentability of your mini-mash wort) and the amount and fermentability of your malt extract.

Why 4.0 lbs. (1.8 kg) of grain? Well, if you pick a reasonable mash thickness for the batch sparge, 4.0 lbs. (1.8 kg) of grain and the required amount of water fill a 2-gallon (7.6 L) cooler almost to the top. In my recipes, I use 1.375 quarts of water per pound of grain (2.9 L/kg). This translates to 5.5 qts. (5.2 L) of water per 4.0 lbs. (1.8 kg) of grain.
From the four pounds (1.8 kg) of grain, you will yield about 20 “gravity points” in a 5-gallon batch. In other words, the partial mash alone will make 5 gallons (19 L) of beer at a specific gravity of 1.020. This is, incidentally, approximately the amount of fermentables that a 3.3-lb. (1.5-kg) can of liquid malt extract yields.

The exact specific gravity you achieve will depend on many variables, most notably what grains you mash and how well they are crushed. For a low-gravity beer, almost half of the fermentables can come from your partial mash.
You can also mash your grains in a 3-gallon (11-L) beverage cooler, using 6 lbs. (2.7 kg) of grain. To convert the recipes in this story to a 3-gallon (11-L) partial mash, add 2.0 lbs. (0.91 kg) of the specified base grain to your recipe and an extra 2.75 quarts (2.6 L) of water to your mash water. Subtract 1 lb. 2 oz. (0.51 kg) of dried malt extract (or 1.5 lbs./0.68 kg liquid malt extract) to account for the added base malt. With a 3-gallon (11-L) partial mash, you can either collect, and boil down, a few more quarts of wort, or you can quit collecting wort when you reach the amount specified in a typical 2.0-gallon (7.6-L) partial mash recipe (around 3.0 gallons (11 L).

Mashing In

To begin your brewing session, heat 5.5 qts. (5.2 L) of water to 11 °F (6.1 °C) over your target mash temperature. While the water is heating, put your crushed grains into a large nylon steeping bag. Tie the bag off at the very end, leaving as much space for the grain to expand as possible. Once the water is heated, pour it into the cooler, then slowly lower the grain bag into the hot water. (Note: you do not need to modify the cooler in any way.)
Use a clean brewing spoon to poke and prod at the bag as you lower it into the hot water. You do not want any pockets of dry grain in the middle of your mash.

Once the bag is submerged, make a mental note of how high the liquid level is in the cooler, then put the lid on and set a timer for 30–45 minutes.
Adding the grain to the water is the point in the procedure you need to be most careful about. Lower the grain bag very slowly into the hot water and use your spoon to vigorously poke at the bag. You may even want to bob the bag up and down slightly as you lower it into the hot water. If you just dunk the bag quickly, and are too dainty with your spoon, it is very possible — almost guaranteed, really — that pockets in the crushed grain will not be in contact with water. If this happens, your extract efficiency can be greatly diminished. So, go slowly — it should take a couple minutes to lower the grain into the water. And, wield your spoon like you mean it.

During the time the mash rests, the starch in the base grains will dissolve and enzymes from the grain will convert the starch to simple sugars. After mashing in (mixing the grain and water), feel around on the cooler. If any part — such as the lid — feels hot, cover that part with a towel or pot holder to conserve heat.
After the mash is completed, you will drain all the wort in the cooler (the first wort), then add more hot water (sparge water) and collect the second volume of wort (the second wort). While the grains are mashing, begin heating 5.5 quarts (5.2 L) of sparge water to 180–190 °F (82–88 °C) in a large kitchen pot. In addition, begin heating 0.5 gallon (1.9 L) of water to a boil in your brewpot.

Collecting the First Wort

After the mash is completed, open the lid on the cooler. Take a beer pitcher or large measuring cup (or any other similar container), hold it below the cooler’s spigot and run off about a couple pints of wort. Pour this wort carefully back into the cooler, on top of the grain bag. Repeat a few times until the wort clears somewhat and no large bits of husk are seen in the runoff. You shouldn’t need to recirculate more than a few quarts total. (Sometimes, especially when light-colored grains are used, the wort won’t seem to clear much as you draw it off. If this happens, don’t worry, the beer will clear during the boil.)

Next, open the spigot and collect all the wort that runs off. Pour this wort immediately into the 0.5 gallon (1.9 L) of boiling water in your brewpot. (Pouring the wort into the boiling water will stop any enzymatic activity and “fix” the fermentability of that wort. This serves the same purpose as a mash out does in a full mash.) When the flow of wort from the spigot slows to a trickle, keep collecting for a minute or so, then stop. You have now collected the first wort from your mash. Keep heating this wort in your kettle while you collect the second wort. When it comes to a boil, adjust your heat to produce a moderate boil.
When collecting your wort from the cooler, tilt the collection vessel so that wort runs down the side. Don’t let the hot wort fly through the air and splash into the bottom of the vessel. Likewise, when you pour wort back on the top of the mash or into your brewpot, pour as “quietly” as possible. If you splash your wort around too much while it is hot, you may prime it to become stale faster during conditioning and aging. Small amounts of wort agitation are inevitable when running the wort off or pouring it into your brewpot, so don’t sweat the small stuff. Do your best to collect and transfer the hot wort with as little splashing as is practical and the quality of your beer will not suffer.

Collecting the Second Wort

Leave the grain bag in the cooler and pour the 180–190 °F (82–88 °C) sparge water you have been heating into the cooler. Fill the cooler to the same fill level as during the mash. This will require slightly less water than before as the grain husks will have absorbed some water during the mash. The combination of 180–190 °F (82–88 °C) water and wet, hot grains should produce a grain bed temperature of less than 170 °F (77 °C). You do not want your grain bed or second wort to exceed 170 °F (77 °C) or you will begin extracting tannins from the wort. This leads to astringency in the finished beer. The first time you try this partial mash procedure, heat the sparge water to 180 °F (82 °C); if the temperature of the grain bed is lower than 170 °F (77 °C), try using hotter sparge water the next time around.Poke around at the grains with your spoon again, then let the mash sit (with the cover on) for about 5 minutes.

Next, recirculate and drain the mash as before. At the end of the runoff, you should tip the cooler to try to collect every last bit of the second wort that you can. With the first and second worts collected, and the 0.5 gallon (1.9 L) of boiling water you started with, you should now have around 3 gallons (11 L) of wort in your kettle. This wort should have a specific gravity around 1.033. (There’s no need to measure it at this point, unless you want to.) Bring this wort back to a boil, add your bittering hops — and dried malt extract, if the recipe calls for it — and begin the 60-minute boil.
One benefit of this procedure is that you do not need to elevate a hot liquor tank above your grain bed, as you do when continual sparging (or fly sparging). You also do not need a “whirligig,” or other device, to deliver the water to your grain bed. In a cramped kitchen, an elevated vessel full of hot water not only takes up precious real estate, it can also be a scalding hazard.

Finishing the Brew

Once you’ve collected your first and second wort and brought it to a boil, finish your beer as you would any “extract late” brew. Boil your hops in the wort from the partial mash (perhaps with some added dried malt extract), but withhold the addition of liquid malt extract until at or near the end of the boil. Make sure the late extract is heated or steeps in hot wort for 15 minutes to sanitize it, but don’t boil, heat or steep it for longer than that.
Next, cool your wort in your brewpot — either with a copper wort chiller or by cooling the pot in your kitchen sink. Once the wort is cool, transfer it to your fermenter and add cool water to make 5 gallons (19 L) of wort. Aerate the wort well and pitch your yeast. Ferment, condition and package your beer as usual.

Cleaning Up

Once your brew day is finished, make sure to clean your mash tun (beverage cooler). If you leave it for later, the wet grains will stink to high heaven when you go to clean it. Wash the cooler in warm, soapy water and let it dry completely — with the lid off — before putting it away. Be sure to drain some soapy water through the spigot while cleaning. Likewise, don’t put the spent grains in your kitchen garbage; it will reek by the next morning.

Conclusion

That’s all there is to it. You can perform this countertop partial mash procedure without a lot of extra equipment — all you need is a cooler and a big grain bag. And, with all the varieties of grain to choose from, you can expand your brewing horizons beyond just steeping specialty grains. Plus, it’s easy to boot. And most importantly, it makes great beer.
Below, I give five recipes that use this technique. And, it’s easy to convert your existing extract recipes to recipes that use this procedure. Take good notes the first time you try this and you will know if there are any tweaks you need to apply the second time.
Whether you’re a dedicated stovetop brewer, or just returning to the kitchen for the occasional indoor brewing session, I think you will like this technique.

This is my house ale, converted to the countertop partial mashing procedure. 48% of the extract weight — the amount of fermentable and non-fermentable sugars that contribute to the original gravity (OG) of the beer — comes from the mini-mash.

Heat 5.5 qts. (5.2 L) of water to 169 °F (76 °C) and mash grains, starting at 158 °F (70 °C), for 30 minutes. While mash is resting, boil 0.5 gallons (1.9 L) of water in your brewpot and heat 5.5 qts. (5.2 L) of water to 180 °F (82 °C) in a large kitchen pot. Recirculate 3 quarts (~3 L) of wort then run off first wort and add it to the boiling water in kettle.

Add 180 °F (82 °C) water to cooler until liquid level is the same as during the first mash. Let rest for 5 minutes, then recirculate and run off second wort. Bring wort to a boil, add dried malt extract and bittering hops and boil for 60 minutes. Add liquid malt extract, molasses, Irish moss and flavor hops with 15 minutes left in boil. After boil, cool wort, transfer to fermenter and add water to make 5 gallons
(19 L). Aerate and pitch yeast. Let ferment at 70 °F (21 °C).

Heat 5.5 qts. (5.2 L) of water to 163 °F (73 °C) and mash maize and crushed grains, starting at 152 °F (67 °C) for 45 minutes. Recirculate, run off first wort and add it to 0.5 gallon (1.9 L) of boiling water in your kettle. Add 190 °F (88 °C) water to cooler, let rest for 5 minutes, then recirculate and run off second wort. Bring wort to a boil, add corn sugar and bittering hops and boil for 60 minutes.

Add Irish moss and yeast nutrients with 15 minutes left in boil. After boil, stir in liquid malt extract and let wort rest (covered) for 15 minutes before cooling. Cool wort, transfer to fermenter and add water to make 5 gallons (19 L). Aerate and pitch yeast. Ferment at 68 °F (20 °C).

There’s really no debate – a great "just-plain-beer" beer is something every homebrewer should have in his recipe file. This extra special bitter (ESB) — well-balanced, with a nice hop flavor and aroma from First Gold hops — will make you a believer in batch sparge partial mashing. 40% of the extract comes from the partial mash.

Put crushed grains in a large nylon steeping bag. Heat 5.5 qts. (5.2 L) of water to 165 °F (74 °C) and pour into your 2-gallon (7.6-L) cooler. Slowly submerge grain bag, using a large brewing spoon to ensure that grain mixes completely with the water. Let mash rest, starting at 154 °F (68 °C) for 30 minutes. While mash is resting, heat 0.75 gallons (2.8 L) of water to a boil in your brewpot and 5.5 qts. (5.2 L) of water to 180 °F (82 °C) in a large kitchen pot. Recirculate by drawing off a pint or two of wort from the cooler and returning it to the top of the mash. Repeat until wort is clear or 3 quarts (~3 L) have been recirculated.

Next, run off entire first wort and add to boiling water in kettle. Add 180 °F (82 °C) water to cooler until liquid level is the same as during the first mash. Let rest for 5 minutes, then recirculate and run off wort as before. Bring wort to a boil, add dried malt extract and bittering hops and boil for 60 minutes. Add liquid malt extract, Irish moss and flavor hops with 15 minutes left in boil.

Add aroma hops with 2 minutes left in boil. After boil, cool wort until side of brewpot is cool to the touch. Transfer wort to fermenter, add water to make 5 gallons (19 L), aerate well and pitch yeast from yeast starter. Let ferment at 70 °F (21 °C). Once wort falls clear after primary fermentation, bottle beer. (I.e. no need to do a "secondary fermentation.")

If you look closely at the works of Leaonardo DaVinci . . . you’re probably at a museum. The Munich malt and mix of hop varieties in this recipe come together like a well-oiled machine. 25% of the extract is from the partial mash. The BYO code: 10/06 8-52 12-74 15-40 17-8 24-4 28-108 41-93 46-13 72-36

Because of its high IBU target, this beer uses the Texas Two-Step method of wort production.
Step One: Put crushed grains in a large nylon steeping bag. Heat 5.5 qts. (5.2 L) of water to 167 °F (75 °C) and pour this water into your 2-gallon (7.6-L) cooler. Slowly submerge grain bag, using a large brewing spoon to ensure that the crushed grain mixes completely with the water.

Let mash rest, starting at 156 °F (69 °C) for 30 minutes. While mash is resting, heat1.0 gallon (3.8 L) of water to a boil in your brewpot and 5.5 qts. (5.2 L) of water to 180 °F (82 °C) in a large kitchen pot. Recirculate by drawing off a pint or two of wort from the cooler and returning it to the top of the mash. Repeat until wort is clear or 3 quarts (~3 L) have been recirculated.

Next, run off entire first wort and add to boiling water in kettle. Add 180 °F (82 °C) water to cooler until liquid level is the same as during the first mash. Let rest for 5 minutes, then recirculate and run off wort as before. Bring wort to a boil, add dried malt extract and bittering hops and boil for 60 minutes. Add hops at times indicated in recipe list. Add Irish moss with 15 minutes left in boil. After boil, cool wort until side of brewpot is cool to the touch.

Cool wort to 70 °F (21 °C) and siphon into fermenting wort from step one. Add water to make 5 gallons (19 L), if needed. Aerate combined wort only if step one wort was not fermenting vigorously. Let ferment at 70 °F (21 °C). Add dry hops in secondary, 4 days before bottling or kegging.

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